1. Field of the Invention
This invention relates to a door lock, more particularly to a lock set which has inner and outer handle assemblies through which a door latch can be operated to latch or unlatch a door.
2. Description of the Related Art
In order to provide door locks with diverse functions desired for different purposes and applications, various forms of lock sets having inner and outer handles have been suggested in the art. One example of such lock sets includes an inner handle assembly provided with a locking spindle having a knob which can be operated by the user from the inside of the door to lock the door, or to lock permanently a lock body mounted inside an outer handle permanently while permitting the outer handle assembly to idle until the locking spindle is operated to an unlocking position.
Another type of lock set has an inner handle assembly which is not provided with any locking spindle and which can be rotated freely even when an outer handle assembly is locked. The outer handle assembly may be locked or unlocked by operating it with a key.
There is still another type of lock set with a freely rotatable inner handle assembly which has no locking spindle and with an outer handle assembly which can be unlocked with a key. But, when the key is withdrawn from the outer handle assembly, the outer handle assembly is locked back.
U.S. Pat. No. 5,788,296 discloses a lock set which includes a hollow outer spindle mounted on an outer handle assembly, a hollow intermediate spindle connected to an inner handle assembly for connection with a door latch, and a turning rod extending inside the intermediate and outer spindles. Two slide plates and two clutch plates are mounted on the turning rod inside the outer spindle. With the clutch plates mounted on the turning rod, the outer handle assembly is permitted to idle when a lock body provided therein is in a locking state. When a key is inserted into the lock body, the lock body can be rotated by turning the key to unlock a door. However, the door must be opened before the key is withdrawn from the lock body. If the key is withdrawn from the lock body, since the key has to be turned back for withdrawal, the lock body can be turned together with the key to its locking position, and the door can be locked back and cannot be opened.